The present invention concerns a modular chair control construction and method incorporating selectable modular seat adjustment mechanisms that provide adjustability and adaptability to a person sitting in a chair incorporating the modular chair control construction. The present invention further concerns chairs that can be assembled from modular components, and more particularly concerns a modular chair construction and method having a movable seat and/or back, such as a synchrotilt chair, where components can be selected for assembly to construct a chair having selected features. Also, the present invention concerns a chair and related method to facilitate on-site assembly, repair, and post-assembly retrofit to allow addition of features to the chair not originally selected when the chair was assembled or purchased.
Synchrotilt chairs include a chair control configured to pivot a back and a seat at proportionally different angular rates of rotation, which are usually proportioned in a manner to reduce "shirt pull" as a person reclines or leans rearwardly in the chair. Known chair controls include a plurality of parts configured to accomplish the synchrotilt movement and to reduce shirt pull, but as a result, known synchrotilt chair controls tend to be relatively expensive and mechanically complex. Due at least in part to the number of parts and complexity, synchrotilt chair controls have typically been manufactured as permanently assembled units having specific features and/or adjustment mechanisms. This allows manufacturers to mass produce the chair controls with minimum assembly expense, and with a desired level of durability, integrity and reliability. However, this also means that if a chair having a different set of features is desired, a completely different chair control must be provided. This can result in substantially inventory carrying costs where chair controls are assembled ahead of schedule in anticipation of future orders. Alternatively, this can also result in long lead times if particular chair controls are assembled only when a sufficient number of orders have been received. Still further, completely different chair controls results in an undesirable proliferation of parts. It is sometimes possible to use an "up level" chair control having "extra" options in place of a lower level chair control in an effort to meet production ship schedules by leaving the "extra" options disconnected or inoperative. But this results in unnecessary expense in the form of wasted parts. Further, it is noted that if a part on the permanently assembled type chair control wears out or is found to be defective, the entire chair control must be thrown away since it is more expensive to repair the unit than simply provide another one.
In most synchrotilt chair controls, the seat is non-adjustably secured to the chair control. One known synchrotilt chair control disclosed in U.S. Pat. No. 5,328,242 (assigned to the present assignee) includes a mechanism for angularly adjusting a seat with respect to a base about an axle. However, the chair control in patent '242 is not modular, and further includes a plurality of parts making the chair control mechanically complex and difficult to repair in the field. Still further, the chair control in patent '242 is not adapted to allow addition of future modifications and/or adjustments to the seat which may be desired.
More broadly, chair improvements are desired to provide adjustability so that a person sitting in the chair can adjust the chair and/or adjust the chair control to their particular physical needs and preferences, and also can adjust the chair and/or chair control to satisfy the particular needs of a task being performed. Preferably, the adjustment mechanism should allow adjustment of the chair with a minimum of effort while sitting in the chair, so that the user does not need to repeatedly stand up to adjust the chair. Improvement is also desired to prevent looseness or play in actuating levers on the adjustment mechanism, and to allow on-site servicing of chairs, such as to remove or replace components. Additional improvement is further desired in chair control constructions so that multiple features can be provided in a compact package having a thin, sleek profile that is aesthetically pleasing and relatively easily incorporated into a chair, yet which is ready manufacturable and assembleable. Still further, present assemblies result in multiple loose or damaged pieces if disassembled for servicing, and further are not constructed for on-site disassembly and replacement of parts of upgrading.
Thus, a chair construction and method of assembly solving the aforementioned problems is desired. In particular, a chair construction including a modular chair control is desired that allows assembly of selected modular components having desired features but that is also sufficiently thin for aesthetics, that allows ready replacement of worn or damaged components, and that allows retrofitting/upgrading of the chair to incorporate additional features.